Prostate cancer is the most commonly diagnosed cancer in men and the second most common cause of cancer deaths among men in the United States. Counseling patients with early stage disease about treatment options is extremely difficult since the relative benefit of different approaches is not known. The evidence to date indicates that there is no clear benefit with invasive intervention over watchful waiting. In addition, little is known about risk factors which predict the transformation of early stage prostate cancer to clinically aggressive disease. This is of particular concern in the VA since more than a third of all veterans are over age 65. The ability to differentiate individuals with early stage prostate cancer from those with disease that will become clinically aggressive would have enormous benefits. It would help allay the anxiety of those with indolent disease and potentially reduce the morbidity and mortality of those with disease likely to become clinically aggressive.